CN107179467B - GIL fault positioning method and system based on grounding current - Google Patents

Abstract

A GIL fault location method and fault location system based on ground current. When an internal short circuit occurs in the GIL, it is necessary to find the gas chamber where the short circuit occurs for disassembly and maintenance. Since the GIL adopts a fully enclosed metal structure and built-in pot insulators, it is difficult to directly locate the fault, and it needs to be indirectly located through the fault characteristics. Commonly used positioning methods include traveling wave positioning, ultrasonic positioning, etc. The invention proposes a positioning method based on the fault current characteristics of the ground network, and identifies the short-circuit position through the amplitude and phase characteristics of the current in the GIL ground network when the fault occurs. Through the complementarity of the amplitude and phase criteria, the difficulty of positioning caused by ground grids with different ground levels is solved.

Description

GIL fault location method and fault location system based on ground current

technical field

This application (note: this case belongs to one application and includes three sets of inventions) belongs to the technical field of electrical equipment operation and maintenance, and especially relates to a GIL fault location method and system based on ground current, which determines the short circuit through the power frequency characteristics of the ground current when the GIL is faulty point location.

Background technique

As a new type of transmission line, SF6 gas-insulated metal-enclosed transmission line (GIL, Gas Insulated Line) has the advantages of large transmission capacity, small footprint, flexible layout, high reliability, maintenance-free, long life, and small impact on the environment. Many advantages. Using the GIL method can solve the problem of erecting transmission lines in special meteorological environments or in special locations. Compared with oil-filled cables and XLPE cables, GIL has a small capacitance per unit length and a long critical transmission distance. At present, typical engineering cases of GIL in China include the 800kV Laxiwa Hydropower Station GIL and the 1000kV Sutong UHV GIL, both of which are installed in tunnels.

The GIL adopts a fully enclosed structure. When the line is short-circuited, it is necessary to determine the faulty gas chamber. After the SF6 gas in the faulty gas chamber is evacuated, the faulty GIL is removed and replaced. Since the maintenance work of GIL is complicated and time-consuming, it is very important to accurately locate the fault location of GIL, which can avoid dismantling the normal gas chamber by mistake, greatly shorten the power outage processing time, and have significant economic benefits.

In the prior art, the principle of traveling wave positioning adopts the principle of high-speed sampling and high-precision GPS synchronization. The voltage traveling wave during a short circuit is obtained through a capacitive coupler, and the position of the short circuit point is calculated by the time difference between the voltage traveling wave and the two sides of the GIL. The principle of traveling wave positioning is simple equipment configuration, only traveling wave acquisition equipment needs to be configured on both sides of the line, but for GIL lines with a small overall length, accurate positioning requires high sampling frequency and synchronization accuracy, and the reliability of the equipment is low. The principle of traveling wave location is susceptible to disturbances in the event of lightning strikes or manipulative waves.

The principle of ultrasonic positioning uses piezoelectric ceramic sensors to collect ultrasonic signals on the GIL shell, and lays ultrasonic sensors along the line to capture ultrasonic signals generated by fault currents in sections, and determines the location of the fault point by the time difference between the ultrasonic signals reaching the sensor. The ultrasonic positioning method has better anti-interference, but the cost of ultrasonic sensors is higher, and the reliability and lifespan are not as good as conventional electrical quantity sensors. Due to the small output signal of the ultrasonic sensor and the limited length of its leads, the acquisition device must be installed near the GIL shell. Due to the need to judge the time difference of signal arrival, the ultrasonic acquisition devices of the whole line need to sample synchronously, and the overall reliability of the system is low.

Therefore, those skilled in the art need to provide a method and system for GIL fault location, which can reliably determine the location interval of the GIL short-circuit point, so as to guide the repair and maintenance work.

Contents of the invention

In order to solve the above technical problems in existing projects, this application provides a GIL fault location method and system based on ground current, which can reliably determine the location interval of GIL short-circuit points, thereby guiding maintenance and repair work.

This application specifically adopts the following technical solutions:

A ground current-based GIL fault location method is characterized in that the short-circuit position of the GIL is identified through the amplitude and phase characteristics of the current in the GIL ground network when the fault occurs.

A GIL fault location method based on ground current, SF6 gas insulated metal-enclosed transmission line GIL, its shell is fixed on the ground through a support frame, grounding copper bars are laid underground, and the GIL shell and support frame are connected to the copper bar ground network nearby ; It is characterized in that, described positioning method comprises the following steps:

Step 1: Set a measuring point at every set distance along the GIL, and set up an on-site acquisition device at each measuring point to measure the current flowing through the grounding copper bar at the measuring point, that is, the amplitude and phase of the grounding current;

Step 2: When the starting signal condition of the local collection device is met, start each local collection device set in step 1, and collect the ground current amplitude and phase at each measuring point on the spot;

Step 3: Judging the ratio of the copper bar resistance per unit length along the GIL longitudinal direction to the soil or concrete resistance per unit length, when the ratio is greater than the preset resistance ratio threshold, go to step 4, otherwise go to step 5;

Step 4: According to the grounding current amplitude of each measuring point flowing through the copper bar collected in step 2, find the measuring point with the largest grounding current amplitude, and judge the section between the left and right measuring points adjacent to this measuring point as GIL failure section;

Step 5: According to the ground current phase of each measuring point flowing through the copper bar collected in step 2, find two adjacent measuring points with opposite grounding current phases, and the section between the two measuring points is the GIL fault section.

further,

In step 1, the current on the grounding copper bar is collected by shunting, that is, the shunt branch is connected in parallel on the grounding copper bar, and the current amplitude and phase on the copper bar are obtained by collecting the current of the shunt branch.

In step 2, the starting signal of the local acquisition device includes the line protection action signal and the copper bar ground current mutation signal, and the logic relationship between the line protection action signal and the copper bar ground current mutation signal is "OR".

In step 2, after the on-site acquisition device is started, the ground current amplitude and phase are calculated according to the current sampling waveforms of 5 power frequency cycles before and after the start time.

In step 3, the set length refers to 10 times the preset positioning accuracy L, that is, the length of 10L, and the preset resistance ratio threshold is 10%.

This application also discloses a GIL location system based on the aforementioned GIL fault location method, the technical solution of which is as follows:

A GIL location system based on the aforementioned GIL fault location method, the GIL location system includes a plurality of on-site acquisition devices, data concentrators and fault location hosts; it is characterized in that:

A plurality of measuring points are set along each GIL to be fault-located, and an on-site acquisition device is installed at each measurement point, and the on-site acquisition device is used to measure the grounding current flowing through the copper bar;

Each GIL line corresponds to a data concentrator, and the data concentrator is used to receive the ground current signal collected by each local collection device in the GIL line;

Each data concentrator uploads all ground current signals in the corresponding GIL line to the fault location host, and the fault location host determines the GIL fault section.

Further, the on-site collection device has a shunt line and a collection terminal, the collection terminal is a feedthrough transformer, the shunt line is connected in parallel to the grounding copper bar, and the feedthrough transformer is sleeved on the shunt line.

The on-site acquisition devices are connected through the RS485 bus and the power supply synchronous bus.

Each data concentrator is connected by optical fiber.

The fault location host obtains the trip signal of the line protection through the MMS or GOOSE network.

The acquisition device installed on site uses power frequency AC220V AC power supply on the same bus. .

Compared with the prior art, the present application has at least the following advantages:

The GIL fault location method based on ground current and the measured signal of the system are power frequency high-energy signals, the acquisition device does not need a special synchronization signal, the sampling frequency is low, the sensor has a long life, and the requirements for the acquisition system hardware are low. The acquisition devices start independently and record the ground current waveform when the fault occurs. The overall redundancy of the system is large and the reliability is extremely high. After adopting the shunt method to obtain the ground current, the collector can be installed near the ground grid, which has nothing to do with the GIL body. It is easy to install and easy to repair and maintain the GIL.

Description of drawings

FIG. 1 is a schematic diagram of a GIL grounding method in the prior art;

Figure 2 is a schematic diagram of the GIL grounding current diffusion method;

Figure 3 is a schematic diagram of the principle of ground current shunt acquisition in the middle GIL;

FIG. 4 is a schematic structural diagram of the GIL fault location system based on ground current in the present application;

Fig. 5 is the schematic flow chart of the GIL fault location method based on the ground current of the present application;

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Referring to FIG. 1 , this figure is a schematic diagram of a GIL grounding method in the prior art.

The GIL shell is fixed on the ground through the support frame, and the grounding copper bar is laid underground, and the GIL shell and the support frame are connected to the copper bar ground network nearby. The longitudinal grounding resistance of GIL is mainly composed of copper bar resistance, and the horizontal grounding resistance is mainly soil resistance or concrete resistance.

Referring to FIG. 2 , this figure is a schematic diagram of a GIL grounding current diffusion method in the prior art. Due to the expansion joint and sliding sealing structure of the GIL shell, the continuity of the electric conduction under the condition of large current cannot be guaranteed. The cross-sectional area of the soil is very large, and its inductance is negligible, mainly the resistance component of the soil. The longitudinal grounding resistance per unit length refers to the resistance of the soil and the copper bar over the length of L meters. Since the resistivity of the copper bar is about 1 billion times lower than that of the soil, when using a standard copper bar of 250 square millimeters, the longitudinal grounding resistance is mainly composed of copper row resistance. The horizontal grounding resistance per unit length refers to the equivalent resistance of the soil diffusion effect on the length of L meters. The grounding copper bar is generally connected to the ground grid. The buried depth of the ground grid is related to the area of the ground grid and the diffusion effect. Considering Due to the constraints of project cost, the ground grid current must spread to a certain area to meet the diffuse current design index.

As shown in Figure 5, this application discloses a GIL fault location method based on ground current. The SF6 gas-insulated metal-enclosed transmission line GIL, its shell is fixed on the ground through a support frame, and ground copper bars are laid underground. The GIL shell The body and the support frame are connected to the copper row ground network nearby; the positioning method includes the following steps:

Step 1: Set up a measuring point at every set distance along the GIL, and set up an on-site acquisition device at each measuring point to measure the current flowing through the grounding copper bar at the measuring point, that is, the amplitude and phase of the grounding current.

Use the shunt method to collect the current on the grounding copper bar, that is, connect the shunt branch on the grounding copper bar in parallel, and obtain the current amplitude and phase on the copper bar by collecting the current of the shunt branch.

As shown in Figure 3, the current component on the copper bar can be obtained in a fixed proportion by connecting the shunt branch on the grounding copper bar in parallel, and the current component of the copper bar can be collected by using the through-hole transformer, so as to calculate the copper bar on the ground current.

Step 2: When the starting signal condition of the local collection device is met, start each local collection device set in step 1, and collect the ground current amplitude and phase at each measuring point on the spot;

The starting signal of the local acquisition device includes the line protection action signal and the copper bar ground current mutation signal, and the logical relationship between the line protection action signal and the copper bar ground current mutation signal is "or".

After the on-site acquisition device is started, the current sampling waveforms of 5 power frequency cycles before and after the start time are calculated according to the current sampling waveforms to calculate the ground current amplitude and phase.

Step 3: Judging the ratio of the copper bar resistance of the set length along the GIL longitudinal direction to the soil or concrete resistance of the set length, when the ratio is greater than the preset resistance ratio threshold, go to step 4, otherwise go to step 5;

In step 3, when the preset positioning accuracy of the application is L meters, the set length is 10L meters, and when the resistance of copper bars per 10L meters is less than 10% of the resistance of soil or concrete per 10L meters, then enter step 5 ; When the copper bar resistance per 10L meter is greater than 10% of the soil or concrete resistance per 10L meter, enter step 4, wherein 10% is the preset resistance ratio threshold.

Step 4: According to the grounding current amplitude of each measuring point flowing through the copper bar collected in step 2, find the measuring point with the largest grounding current amplitude, and judge the section between the left and right measuring points adjacent to this measuring point as GIL failure section;

The judgment logic is: first compare the ground current amplitudes of each measuring point one by one, find out the measuring point N with the largest current amplitude, and then determine the GIL fault section from measuring point N-1 to measuring point N+1.

Step 5: According to the ground current phase of each measuring point flowing through the copper bar collected in step 2, find two adjacent measuring points with opposite grounding current phases, and the section between the two measuring points is the GIL fault section.

The judgment logic is: first compare the ground current phases of each measuring point one by one, and the phase between measuring point N and measuring point N+1 is opposite, and then determine that the GIL fault section is from measuring point N to measuring point N+1.

As shown in Figures 3 and 4, the present application also discloses a GIL locating system based on the aforementioned GIL fault locating method. The GIL locating system includes a plurality of on-site acquisition devices, a data concentrator, and a fault locating host.

A plurality of measuring points are set along each GIL to be fault-located, and an on-site acquisition device is installed at each measurement point, and the on-site acquisition device is used to measure the ground current flowing through the copper bar; the on-site acquisition device A shunt line and a collection terminal, the collection terminal is a feedthrough transformer, the shunt line is connected in parallel to the grounding copper bar, and the feedthrough transformer is sleeved on the shunt line. Each GIL line is correspondingly equipped with a data concentrator, and the data concentrator is used to receive the ground current signal collected by each local collection device in the GIL line. The on-site acquisition devices are connected through the RS485 bus and the power supply synchronization bus, and the data concentrators are connected through optical fibers. Each data concentrator uploads all ground current signals in the corresponding GIL line to the fault location host, and the fault location host determines the GIL fault section.

The fault location host obtains the trip signal of the line protection through the MMS or GOOSE network. The acquisition device installed on site uses power frequency AC220V AC power supply on the same bus. .

The on-site collection device is installed on the GIL ground network along the line, and collects the ground current of the copper bar through the shunt lead wire and the core transformer; the data concentrator is set at a certain distance along the longitudinal direction of the GIL, and the scattered on-site Acquisition device; the data concentrator is connected to the fault location host through optical fiber Ethernet, collects the data collected by the collector and transmits it to the data concentrator, and broadcasts the start signal of the fault location host to the local collection device; centrally sets up a fault location The host computer collects the current amplitude and phase information of the whole line, and locates the fault. The host computer obtains the trip signal of the line protection through the MMS or GOOSE network, and forwards the trip signal to all local acquisition devices through the data concentrator. The on-site acquisition device can use the centralized line protection action signal as the start signal, or the sudden change in copper bar current as the start signal, and the two are "or" logic. After the on-site acquisition device is started, the current sampling waveforms of 5 power frequency cycles before and after the start time are stored in the EEPROM chip of the device, and will not be lost in case of power failure. After the line fault, the fault location host collects the sampling data of the whole line by calling, and calculates the amplitude and phase of the current at each point, which is used for the location and judgment of the fault point. Since the internal insulation damage of GIL cannot be recovered, it is not necessary to consider the logic of multiple starts caused by line reclosing when locating.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent of equivalent change Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (11)

1. a kind of GIL Fault Locating Method based on earth current, SF6 gas-insulated metal closed power transmission line GIL, shell It is fixed on the ground by support frame, provided underground grounding copper bar, GIL shell and support frame access copper bar earth mat nearby；It is special Sign is, the localization method the following steps are included:

Step 1: one measuring point being set every set distance along GIL, is flowed through in each measuring point setting in-site collecting device for measuring Electric current, that is, earth current the amplitude and phase of grounding copper bar at the measuring point；

Step 2: when meeting in-site collecting device enabling signal condition, then each in-site collecting device set by starting step 1, Earth current amplitude and phase at each measuring point of in-site collecting；

Step 3: judging the ratio along the copper bar resistance of the setting length of the longitudinal direction GIL and the soil of setting length or concrete resistance Value enters step 4, otherwise enters step 5 when the ratio is greater than preset resistance ratio threshold value；

Step 4: flowing through the earth current amplitude of copper bar according to each measuring point that step 2 acquires, find out earth current amplitude maximum Measuring point, the section between two measuring point of left and right adjacent with the measuring point are judged as GIL fault section；

Step 5: flowing through the earth current phase of copper bar according to each measuring point that step 2 acquires, find earth current opposite in phase Two neighboring measuring point, the section between two measuring point is GIL fault section.

2. the GIL Fault Locating Method according to claim 1 based on earth current, it is characterised in that:

In step 1, acquire the electric current on grounding copper bar using the mode of shunting, i.e., the parallel shunt branch on grounding copper bar, The current amplitude and phase on copper bar are obtained by way of acquiring diverter branch electric current.

3. the GIL Fault Locating Method according to claim 1 based on earth current, it is characterised in that:

In step 2, in-site collecting device enabling signal includes route protection action signal and copper bar earth current Sudden Changing Rate letter Number, route protection action signal and copper bar earth current Sudden Changing Rate signal are the logical relation of "or".

4. the GIL Fault Locating Method according to claim 3 based on earth current, it is characterised in that:

In step 2, after the starting of in-site collecting device, according to the current sample waveform of 5 power frequency periods each before and after Startup time Calculate earth current amplitude and phase.

5. the GIL Fault Locating Method according to claim 1 based on earth current, it is characterised in that:

In step 3, the setting length refers to 10 times of default positioning accuracy L i.e. 10L length, the preset resistance ratio Threshold value is 10%.

6. the GIL fault location system of GIL Fault Locating Method described in a kind of any one of claim 1-5 claim, institute Stating GIL fault location system includes multiple in-site collecting devices, data concentrator and fault location host；It is characterized by:

Multiple measuring points are set along the GIL that each waits for fault location, goes out in each measuring point and in-site collecting device is installed, it is described In-site collecting device is for measuring the earth current for flowing through copper bar；

As soon as each GIL route is correspondingly arranged a data concentrator, the data concentrator is each in this GIL route for receiving Ground acquisition device earth current signal collected；

All earth current signals in corresponding GIL route are uploaded to fault location host by each data concentrator, by event Barrier positioning host judges GIL fault section.

7. GIL fault location system according to claim 6, it is characterised in that:

The in-site collecting device shunt line and acquisition terminal, the acquisition terminal are punching mutual inductor, and shunt line is connected in parallel on On grounding copper bar, punching mutual inductor is set on shunt line.

8. GIL fault location system according to claim 6, it is characterised in that:

It is connected by RS485 bus with power supply synchronous bus between each in-site collecting device.

9. GIL fault location system according to claim 6, it is characterised in that:

Each data concentrator is connected by optical fiber.

10. GIL fault location system according to claim 6, it is characterised in that:

The fault location host obtains the trip signal of route protection by MMS or GOOSE network.

11. GIL fault location system according to claim 6, it is characterised in that:

Local mounted acquisition device is connected using the power frequency AC220V Alternating Current Power Supply on same bus, for electrical connection using handing in hand Connect mode, acquisition device also acquires AC220V alternating supply voltage while acquiring copper bar electric current, use supply voltage as The reference phase of phase measurement.